Recording-reproducing device



Patented June 19, 1945 RECORDING-REPRODUCING DEVICE Semi Joseph Begun,Cleveland Heights, Ohio, as-

signor to The Brush Development Company, Cleveland, Ohio, a corporationof Ohio Application November 26, 1942, Serial No. 467,041

5 Claims.

This invention relates to transient analyzer systems, and moreparticularly to systems of the type described in my application SerialNo. 425,304, filed January 1, 1942, which are effec tive in recording atransient signal which may occur at an unpredictable instant, and incyclically reproducing the recorded signal so as to make it possible tostudy the signal on a cyclically-operative indicating device, such as anoscilloscope.

Among the objects of the present invention are transient analyzersystems of the foregoing type which make it possible to studysimultaneously two or more transient phenomena which may occursubstantially simultaneously.

The foregoing and other objects of the invention will be best understoodfrom the following description of exemplifications thereof, referencebeing had to the accompanying drawing wherein.

Figure 1 is a block diagram of the circuit of my device for establishingthe time phase relationship between two or more transient signals.

Figure 2 is a view of the record obtained from the device shown inFigure 1.

My device as shown in Figure 1 has an endless magnetic recording pathsuch as the tape I which is continuously driven around the rollers II,H! at a constant rate of speed by the motor I3. Three recording headsI4, I5, I6, are associated with the magnetic tape III for recordingsimultaneously on three separate portions of the tape. Each head isconnected to a source of transient signal. As shown. the recording headI4 is connected to signal input terminals I! which are adapted to beconnected to a line in which a transient signal is expected in such amanner that the power transient signal will be recorded on one portionof the tape I 0. The recording head I5 is connected to signal inputterminals I8 which are adapted to be connected to the same line in whicha transient signal is expected but in such a manner that the currenttransient signal will be recorded on another portion of the tape I0; andthe recording head I6 is connected to signal input terminals I9 whichare adapted to be connected to the same line but in such a manner thatthe voltage transient signal will be recorded on a third portion of thetape I0.

Although I describe my invention in connection with power, current, andvoltage transient signals from one line, it is to be realized that manyother types of transient signals can be recorded and that the transientsneed not necessarily arise from just one line.

The power input terminals H are connected to a modulator 20, and themodulator is connected to an oscillator 23 which supplies carriercurrent to the modulator. The power transient signal modulates thecarrier current and the resulting signal is amplified by the amplifier24 and passed to the recording head I4 which records the transientsignal modulated carrier on the moving magnetic tape ID. A similararrangement is used for the other two input terminals I8, I9. The signalapplied at I8 is used in the modulator 2I to modulate the carriercurrent which is obtained from the same oscillator 23, and the signalapplied at I9 is used in the modulator 22 to modulate the carriercurrent which is also obtained from the oscillator 23. Obviously, mysystem can be used without the carrier current by directly recording a.facsimile of the transient on the magnetic tape.

The two transient signal modulated carrier currents are amplified byamplifiers 25, 26 and are passed to the recording heads I5, I6respectively, and the portion of the magnetic tape I0 which passes undereach head is magnetized in accordance with the signal current in thehead.

Three obliterating heads 30, 3|, 32 are provided in association with themagnetic tape I0, and positionednear each recording head I4, I5, I6 forobliterating the signal on a portion of the tape just before thatportion reaches the next recording head. Each of the three obliteratingheads is connected to the oscillator 23 which supplies alternatingcurrent to the heads.

Normally when my device is in operation and prior to the occurrence of atransient, the tape I0 is continuously rotating, and each of the headsrecords an unmodulated carrier current on the tape. This unmodulatedcarrier signal is obliterated from the tape as the tape passes under thenext obliterating head thereby clearing the tape for the next recordinghead to record an unmodulated signal. When a transient signal is appliedat the input terminals I'I, I8, I9, the carrier current supplied by theoscillator 23 to the modulators 20, 2I, 22 is modulated in accordancewith the power, current, and voltage transient signals respectively, andis recorded on three separate portions of the tape ID by the recordingheads I4, I5, I6, respectively. The occurrence of the transient alsocauses an impulse to be trans- 'mitted through connections 33, 34, and35 to a trigger circuit 36 to start the operation of the triggercircuit. This impulse may occur in only one of the several connections33, 34, 35, but this one impulse will fire the trigger circuit 36. Or

the impulse may be in more than one of the several connections 33, 34,35, in which case the trigger circuit will be fired in response to thefirst impulse. After a time delay which is slightly less than the lengthof time necessary for any incremental portion of the tape H] to passfrom a recording head to the next obliterating head, the trigger circuit35 causes a timing signal impulse generator 38 to apply a short timingpulse to each of the amplifiers 24, 25, 26, thereby causing a shorttimin pulse to be applied to each of the recording heads l4, l5, l6, andcausing a short timing ignal to be recorded simultaneously on each ofthree portions of the tape Ill. The trigger circuit also energizes therelay 39 to cause it to throw the switch 31. This operation is performedafter the timing signal has been recorded on the tape it and before thefirst part or" the recorded transient signal has reached an obliteratinghead.

Throwing switch 3? breaks the circuit from the oscillator 23 to theobliterating heads 38, 3t,

thereby preventing the obliteration of the previously recorded transientsignal and also breaks the circuit from the oscillator 23 to themodulators 2, 22, to prevent the carrier from being recorded on theportions of the tape on which the transient signal is recorded, therebytrapping the three transient signals on the tape l3. '1 re switch ishown for convenience as a rela}; operated mechanical switch. It is to beunderstood an electronic switch can be used For extremely rapid o;ration the toll would probably be preferable.

will be recorded and reignals. one corresponding (1 power transient onecorrespondi g to the t transient, one correspon to the t ansient, and htransient signal till ing signal. It is known each oithe three recordedtiming signals was made at the same instant. Accordingly, this shorttiming signal associated with each or the traces of the transientsignals will establish an i dex for comparing the time phase relation ofeach of the transient signals with respect to the other two transientsignals.

convenient way of comparing the traces of transient signals is toreproduce the signals ecorded on the ta e ii! by the magnetic repro- 2The signal picked up by the rechewed by a short .e d :15 is amplified atand demod- L t and t output is used to actuate an oscillograoh "=3accordance with the transient in and timing signals which were recordedon tape A light source 32* is provided and is focused through screens 5%52 onto a mirror in the oscil- Zograph id The reflection of the lightfrom the source is applied to a moving film 52 to record a permanenttrace of the excursions or" the mirror. After the tape it has beenrotated one complete turn past the reproducing head :15 the threetransient signal traces and the three timing signal traces will appearon the fill After development the film can be cut into three portions53, 54, 55, as shown in Figure 2, and connected to abase 56. By aligningthe three traces 5?, c8, 59 of the timing pulse in a straight line itwill be easy to study the time phase relation of the three transienttraces 6G, 6!. 82.

By using my aforedescribed system of produc ing simultaneously threetiming pulses, it is possible to use three separate magnetic materialsdriven, if desired, by three separate motors. Each pulse is applied toone magnetic material, and upon reproduction and comparison of the threerecords the operator can determine the time phase relation between thevarious signals. When the three magnetic materials are driven by threeseparate motors, it is desirable that the speeds be the same, or that aknown fixed relation between the speeds be established.

The copending application Serial No. 462,395, filed October 17, 1942, byJ. P. Arndt, Jr., and assigned to the assignee of the presentapplication, describes in connection with Fi 4 circuits of the typesuitable for use in systems of the invention described and claimedherein.

Although the principles of the present invention have been describedabove as applied to one particular type of magnetic recording, they areobviously also applicable to all types of magnetic recording, namely,longitudinal recording, perpendicular r cording and transverserecording.

It will be apparent to those skilled in the art that the novelprinciples of the invention 'disclosed herein in connection withspecific exemplifications thereof will suggest various othermodifications and applications of the same. It is accordingly desiredthat in construing the breadth of the appended claims they shall not belimited to the specific exemplifications of the invention describedherein.

I claim as invention:

in a system for reproducing characteristic or transient electricoccurrences of an rmin conditions: a plurality of c t ns sion channelsconnected to pass electric rient occurrence and a second ectrlc trarsieoccurrence; an endlessly ac":- .--g magnetic recording medium having agiven recording leng'h; dr ing means for driving recording medium so itoperates during a continuous r led in successive cycles throughout itslength; recordim for magnetically recording on said medium said firstand said second transient occurrences; obliterating means forobliterating the magnetic records of said recordrnedium: 'gger meansinterconnected to 1 the operation of said recording means and means;said trigger means being se said recording means to conon said mediumelectric occurough said channels; said trigger ive response to atransient occurrence ass 'hrough a channel to stop the obliterating ope.tion and recording operation.

2. In a system for reproducing characteristic images of transientelectric occurrences of an electric circuit system which operates underpredetermined normal conditions: a plurality of electric transmissionchannels connected to pass a first electric transient occurrence and asecond electric transient occurrence; an endlessly acting magneticrecording medium having a given recording length; driving means fordriving said recording medium so that it operates during a continuousperiod in successive cycles throughout its length; recording means formagnetically recording on said medium said first and said secondtransient occurrences; obliterating means for obliterating the magneticrecords of said recording medium; trigger means interconnected tocontrcl the operation of said recording means and said obliteratingmeans; said trigger means being operative to cause said. recording meansto continuously record on said medium electric occurrences passedthrough said channels; said cor passe t means being on trigger meansbeing operative in response to a transient occurrence passed through achannel to stop the obliterating operation and to stop the recordingoperation a predetermined time interval thereafter.

3. In a system for reproducing characteristic images of transientelectric occurrences of an electric circuit system which operates underpredetermined normal conditions: a plurality of electric transmissionchannels connected to pass a first electric transient occurrence and asecond electric transient occurrence; an endlessly acting magneticrecording medium having a given recording length; driving means fordriving said recording medium so that it operates during a continuousperiod in successive cycles throughout its length; recording means formagnetically recording on said medium said first and said secondtransient occurrences; obliterating means for obliterating the magneticrecords of said recording medium; trigger means interconnected tocontrol the operation of said recording means and said obliteratingmeans; an electric timing signal source operative to be interconnectedwith said recording means for recording timing signals on said recordingmedium; and reproducing means operative to reproduce the magneticrecords recorded on said recording medium; said trigger means beingoperative to cause said recording means to continuously record on saidmedium electric occurrences passed through said channels and tocontrollably record timing signals of said source; said trigger meansbeing operative in response to a transient occurrence passed through achannel to stop the obliterating operation and recording operation.

4. In a system for reproducing characteristic images or transientelectric occurrences of an electric circuit system which operates underpredetermined normal conditions: a plurality of electric transmissionchannels connected to pass recording on said medium said first and saidsecond transient occurrences; obliterating means for obliterating themagnetic records of said recording medium; trigger means interconnectedto control the operation of said recording means and said obliteratingmeans; an electric timing signal source operative to be interconnectedwith said recording means for recording timing signals on said recordingmedium; and reproducing means operative to reproduce the magneticrecords recorded on said recording medium; said trigger means beingoperative to cause said recording means to continuously record on saidmedium electric occurrences passed through said channels and tocontrollably record timing signals of said source; said trigger meansbeing operative in response to a transient occurrence passed through achannel to stop the obliterating operation and to stop the recordingoperation a predetermined time interval thereafter.

5. In a system for reproducing characteristic images of transientelectric occurrences of an electric circuit system which operates underpredetermined normal conditions: a plurality of electric transmissionchannels connected to pass a first electric transient occurrence and asecond electric transient occurrence; an endlessly acting magneticrecording medium having a given recording length; driving means fordriving said recording medium so that it operates during a continuousperiod in successive cycles throughout its length; recording means formagnetically recording on said medium said first and said secondtransient occurrences; obliterating means for obliterating the magneticrecords of said recording medium; trigger means interconnected tocontrol the operation of said recording means and said obliteratingmeans; said trigger means being operative to cause said recording meansto continuously record on said medium electric occurrences passedthrough said channels; said trigger means being also operative inresponse to a transient occurrence to cause. said recording means torecord a timing signal on said recording medium; said trigger meansbeing operative in response to a transient occurrence passed through achannel to stop the obliterating operation and to stop the recordingoperation a predetermined time interval thereafter.

SEMI JOSEPH BEGUN.

